Fail Of The Week: Supercapacitor Spot Welder

August 15, 2019 by Al Williams 33 Comments

[Julian] needed to weld a bit of nickel to some steel and decided to use a spot welding technique. Of course he didn’t have a spot welder sitting around. Since these are fairly simple machines so [Julian] set out to build a spot welder using a charged supercapacitor. The fundamentals all seem to be there — the supercap is a 100 Farad unit and with a charge of 2.6V, that works out to over 300 joules — yet it simply doesn’t work.

The problem is in how the discharge energy is being directed. Just using the capacitor would cause the charge to flow out as a spark when you got near the point to discharge. To combat this, [Julian] put a microswitch between the capacitor and the copper point he expected to use as the welding tip. The microswitch, of course, is probably not the best for carrying a large surge of current, so we suspect that may be part of why he didn’t get great results.

The other thing we noticed is that he used a single point and used the workpiece as a ground return. Most spot welders use two points near each other or on each side of the workpiece. The current from the capacitor is probably just absorbed by the relatively large piece of metal.

The second video below from [American Tech] shows a 500F capacitor doing spot welding with little more than two wires and it seems to work. Hackaday’s own [Sean Boyce] even made one out of some whopping 3000F caps. It did work, although he’s been pursuing improvements.

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DIY PC Test Bench Puts Hardware Troubleshooting Out In The Open

August 15, 2019 by Adam Fabio 20 Comments

If you’ve built a few PCs, you know how frustrating troubleshooting can be. Finding a faulty component inside the cramped confines of a case can be painful — whether its literal when sharp edges draw blood, or just figurative when you have to open that cramped case multiple times to make adjustments.

[Colonel Camp] decided to make life a bit easier by building this PC test bench which makes component troubleshooting much easier and can be built with old parts you probably have lying around. [Camp] was inspired by an old Linus PC Tech Tips video on the same topic. The key to the build is an old PC case. These cases are often riveted together, s a drill makes quick work of disassembling the chassis to easily get to all of the components. The motherboard pan and rear panel/card cage become the top shelf of the test bench, while the outer shell of the case becomes the base and a storage area. Two pieces of lumber support the upper shelf. The build was primed and painted with several coats of grey.

[Camp] built up his testbench with a modest motherboard, cooler and a 970 video card. He loaded up Manjaro Linux to verify everything worked. The basic hardware has already been replaced with a new system including a ridiculously huge cooler. But that’s all in a day’s work for a test bench PC.

We’ve seen some wild workbenches over the years, and this one fits right in for all your PC projects. Check out the video after the break!

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Control The Suck With This Manual Vacuum Pick-And-Place Tool

August 14, 2019 by Dan Maloney 10 Comments

The tapes that surface-mount devices come in may be optimized for automated pick and place, but woe betide those who try to dig components out manually. No matter what size package, the well on the tape seems to be just a wee bit too small to allow tweezers to grip it, so you end up picking the thing up edgewise or worse, pinching too tight and launching the tiny thing into The Void. We hope you ordered extra.

Such circumstances are why vacuum handlers were invented, but useful as they are for picking and placing SMDs, they aren’t perfect. [Steve Gardener]’s sub-optimal experience with such tools led him to build this custom vacuum pick-and-place tool. It’s based on an off-the-shelf Weller unit, of which only the handpiece remains. A bigger, more powerful vacuum pump is joined in a custom enclosure by a PCB with a PIC18F13K22 microcontroller, a power supply, a solenoid to control the vacuum, and a relay to switch the pump. A footswitch starts the pump and closes the vacuum vent; letting off the pedal opens the vent to drop the part, while the pump keeps running for a variable time. This lets him rapidly work through a series of parts without having to build vacuum back up between picks. The video below shows the build and the tool in action.

We love the idea of this tool, and the polished look is pretty slick too. If manual pick-and-place isn’t for you, though, maybe converting a 3D-printer into an automated PnP is something to check out.

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Print Your Own Heat Shrink Labels For Factory-Chic Wire Naming

August 14, 2019 by Al Williams 67 Comments

Heat shrink tubing is great for insulating wires. Labeling wires in a bundle is always useful, too. [Voltlog] has a cheap Brother label printer and discovered he can buy knock off label cassettes for a lot less from China. However, he also found something else: cassettes with heat shrink tubing in them made for the same kind of printer. Could he use the heat shrink cassettes to make neat wire labels? In his first video the answer was sort of, but not really. However, he later had a breakthrough and made a second video explaining how to do it. You can see both videos, below.

At first, the printer didn’t even want to recognize the cassette. It seems like Brother doesn’t want you using exotic tapes with cheap printers. No worry, this isn’t sophisticated DRM, just a sense hole that you need to cover with tape. This discovery was made using the extremely scientific trick of covering all the holes that were not on a regular cassette.

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Shop-Made Tools Turn Cheap Steel Into Telescoping Tubes

August 13, 2019 by Dan Maloney 24 Comments

Beginning metalworkers are often surprised at just how cheap steel can be. It’s a commodity made by the gigaton, and there are always plenty of extra pieces and scraps left over from big projects that are available for pennies a pound. But what you’ve got is often not what you need, especially when it’s steel tubing with welded seams that prevents one tube from fitting inside another.

[Jason Marburger] from Fireball Tool has some great tips for cleaning interior welds in steel tubing. The first part of the video below details manual methods for cleaning off seam welds, including chiseling, sanding with a narrow belt sander, and grinding them down with a die grinder. Those all work well, but only for short lengths of tubing. Longer tubes need special treatment, which is where the clever tools [Jason] designed come in handy.

By attaching a chunk of high-speed steel to a slug made from the next size tube down and driving it through the tube to be cleaned with a hefty piece of threaded rod, he basically created ain internal shaper to shave the weld down. It works like a charm, as does the tool he made for round tubing by laying a bead of hard facing welding rod around the edge of a mild steel slug. Driving this tool into the seamed round tubing with a shop press cleaned up the weld nicely too.

Hats off to [Jason] for coming up with a couple of great shop tips to keep in mind. We’ve seen similar expedient tools for metalworking lately, like this homemade die-punching tool and a linear track to keep your plasma cutter in line.

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NanoVNA Is A $50 Vector Network Analyzer

August 11, 2019 by Al Williams 45 Comments

There was a time when oscilloscopes were big and expensive. Now you can get scopes of various sizes and capabilities on nearly any budget. Vector network analyzers — VNAs — haven’t had quite the same proliferation, but NanoVNA may change that. [IMSAI Guy] bought one for about $50 and made a series of videos about it. Spoiler alert: he likes it. You can see one of the several videos he’s posted, below.

NanoVNA is tiny but sweeps from 50 kHz to 900 MHz and has a touch screen. The device uses a rechargeable battery if you need to haul it up to an antenna tower, for example. Just as a quick test, you can see early in the video the analysis of a rubber duck antenna. The device shows return loss as a plot and you can use a cursor to precisely measure the values. It also shows a Smith chart of the reactance.

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Stepper-Controlled Chop Saw Automates A Tedious Job

August 10, 2019 by Dan Maloney 23 Comments

We’re not going to question why [Absorber Of Light] needs to cut a bazillion little fragments of aluminum stock. We assume his reasoning is sound, so all we’re interested in is the automated chop saw he built to make the job less tedious, and potentially less finger-choppy.

There are probably many ways to go about this job, but [Absorber] leaves few clues as to why he chose this particular setup. Whatever the reason, the build looks like fun, with a long, stepper-driven threaded rod pushing a follower down a track to a standard chop saw. The aluminum stock rides in the track and gets pushed out a set amount before being lopped off cleanly as the running saw is lowered by a linear actuator. The cycle then repeats until the stock is gone.

An Arduino controls the stock-advance stepper in the usual way, but the control method for the linear actuator is somewhat unconventional. A second stepper motor has two cams offset by 180° on the shaft. The cams actuate four microswitches which are set up in an H-bridge configuration. The stepper swivels back and forth to run the linear actuator first in one direction then the other, with a neutral position in between. It’s an interesting approach using mechanical rather than the typical optical isolation. Check it out in action in the video below.

We’ll admit to some curiosity as to the use of the coupons this rig produces, so maybe we’ll get lucky with some details from [Absorber Of Light] in the comment section. After all, we knew exactly what the brass tubes being cut by the similar “Auto Mega Cut-O-Matic” were being used for.

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